package org.apache.lucene.search.function;

/**
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

import org.apache.lucene.index.IndexReader;
import org.apache.lucene.search.FieldCache;
import org.apache.lucene.search.function.DocValues;

import java.io.IOException;

/**
 * Expert: obtains float field values from the
 * {@link org.apache.lucene.search.FieldCache FieldCache} using
 * <code>getFloats()</code> and makes those values available as other numeric
 * types, casting as needed.
 * 
 * <p>
 * <font color="#FF0000"> WARNING: The status of the <b>search.function</b>
 * package is experimental. The APIs introduced here might change in the future
 * and will not be supported anymore in such a case.</font>
 * 
 * @see org.apache.lucene.search.function.FieldCacheSource for requirements on
 *      the field.
 * 
 * @author yonik
 */
public class FloatFieldSource extends FieldCacheSource {
	private FieldCache.FloatParser parser;

	/**
	 * Create a cached float field source with default string-to-float parser.
	 */
	public FloatFieldSource(String field) {
		this(field, null);
	}

	/**
	 * Create a cached float field source with a specific string-to-float
	 * parser.
	 */
	public FloatFieldSource(String field, FieldCache.FloatParser parser) {
		super(field);
		this.parser = parser;
	}

	/*
	 * (non-Javadoc)
	 * 
	 * @see org.apache.lucene.search.function.ValueSource#description()
	 */
	public String description() {
		return "float(" + super.description() + ')';
	}

	/*
	 * (non-Javadoc)
	 * 
	 * @see org.apache.lucene.search.function.FieldCacheSource#getCachedValues(org.apache.lucene.search.FieldCache,
	 *      java.lang.String, org.apache.lucene.index.IndexReader)
	 */
	public DocValues getCachedFieldValues(FieldCache cache, String field,
			IndexReader reader) throws IOException {
		final float[] arr = (parser == null) ? cache.getFloats(reader, field)
				: cache.getFloats(reader, field, parser);
		return new DocValues() {
			/*
			 * (non-Javadoc)
			 * 
			 * @see org.apache.lucene.search.function.DocValues#floatVal(int)
			 */
			public float floatVal(int doc) {
				return arr[doc];
			}

			/*
			 * (non-Javadoc)
			 * 
			 * @see org.apache.lucene.search.function.DocValues#toString(int)
			 */
			public String toString(int doc) {
				return description() + '=' + arr[doc];
			}

			/*
			 * (non-Javadoc)
			 * 
			 * @see org.apache.lucene.search.function.DocValues#getInnerArray()
			 */
			Object getInnerArray() {
				return arr;
			}
		};
	}

	/*
	 * (non-Javadoc)
	 * 
	 * @see org.apache.lucene.search.function.FieldCacheSource#cachedFieldSourceEquals(org.apache.lucene.search.function.FieldCacheSource)
	 */
	public boolean cachedFieldSourceEquals(FieldCacheSource o) {
		if (o.getClass() != FloatFieldSource.class) {
			return false;
		}
		FloatFieldSource other = (FloatFieldSource) o;
		return this.parser == null ? other.parser == null : this.parser
				.getClass() == other.parser.getClass();
	}

	/*
	 * (non-Javadoc)
	 * 
	 * @see org.apache.lucene.search.function.FieldCacheSource#cachedFieldSourceHashCode()
	 */
	public int cachedFieldSourceHashCode() {
		return parser == null ? Float.class.hashCode() : parser.getClass()
				.hashCode();
	}
}